My point was not to take the position that karma is an unimportant number in a computer somewhere, but that people often claim as much in defense of various scoring systems on sites like this and Reddit and so on that create perverse incentives for the users.
I work on online videogames. You don't need to tell me the value of a number in a computer somewhere that means a whole heck of a lot to someone, and shapes how they act. :-)